Lubrication

Rotary valves should be oiled regularly at the end bearings with a good quality light machine oil such as Singer oil. The job can be done more neatly with a precision oiler which has a needle applicator (available from electronics stores).

Light valve oil should be used inside the valves. Remove the tuning slides and drop 3 or 4 drops into each valve. Try to get the valve oil down the slide tubes without it touching the sides as this will remove some of the slide grease and get it into the valves necessitating regreasing of the slides and more frequent cleaning of the valves. Incidentally, I find wool fat (available from the chemist) to be an excellent and inexpensive tuning slide lubricant.

Over a period of time old valve oil thickens and, in combination with scale and corrosion, makes the valves sluggish. Regular use of fresh oil will thin the old oil temporarily but eventually the valves must be cleaned.

Rotary Valves can be flushed with kerosene and with warm soapy water to remove some of the old oil but to do a thorough job they must be taken apart and cleaned.

Disassembly

You will need the following tools, etc. to work on
rotary valves:
-Screwdrivers to fit rotor stop screws and rotor stop
string screws
-An old toothbrush and/or a valve brush

-A rawhide or wooden mallet
-A piece of 25mm dowel 50mm long with a 10mm
hole drilled in one end to a depth of l0mm (optional)
-An apron or towel for your lap (so that parts don't
fall on the floor when working in your lap)
-A work bench covered with an old towel (to absorb
water and keep small parts from rolling away)

N.B. -parts from different valves must never be
interchanged. Always check that all parts are clearly
marked as they are disassembled. If the markings
are not clear, re-mark then (e.g. with 1,2 or 3 lines or
dots scratched into a non-contact surface on parts
of the 1st, 2nd and 3rd valves respectively).

First remove the old valve strings if you wish to replace them. Make sure the
valve levers don't snap up and hit any of the tubing.

Next remove the valve caps. Then turn the instrument over and lay it in your lap
on the apron or towel. The next part of the operation is done in your lap
because you will be tapping on the rotor ends and your lap provides a secure,
padded surface where the impact of the mallet isn't carried through to damage any
part of the instrument that may otherwise be in contact with the table.

Loosen the first rotor stop screw 1/2 turn and, with the screwdriver blade
squarely and firmly in the screw slot, tap the end of the screwdriver handle
until the screw head is again in contact with the rotor spindle end. It's possible to bend or break off the screw head if the screwdriver blade isn't exactly centred and square in the screw head slot. Loosen the
screw another turn and repeat the process until the rotor and back bearing fall
out into your lap. Alternatively the rotors can be removed by first removing the rotor stop screw entirely tapping the spindle end with the thin end of a chopstick or thin dowel. This method avoids the possibility of damaging the screw but care must be taken not to damage the threads in the rotor stop screw hole, or get a piece of the dowel stuck in the hole. When the rotor and back bearing are free, check that both parts are clearly marked and place them on the work bench. Disassemble the remaining valves in the same manner.

Cleaning

Soak rotors, back bearings and rotor caps in hot water with detergent. Scrub each part with an old toothbrush. Deposits. of corrosion and scale may be scraped gently with your fingernail but never use metal, steel wool or abrasives to clean
valve parts. Stubborn corrosion and other deposits must be removed chemically by Campbell Brasswind Service.

Rinse all parts and set then out on the work bench ready for assembly.

Clean the valve casings with hot detergent water and a toothbrush or valve casing brush. Rinse.

Assembly

Take the first rotor and put a drop of machine oil on the rotor spindle and a few drops of light valve oil on the middle part of the rotor. Put it immediately into the correct valve case ensuring that no dirt gets in. Put a drop of machine oil on the back bearing and slip into place on the rotor. Line up the positioning marks on the back bearing and the edge of the valve case. Tap the back bearing into place by placing the piece of dowel on the back bearing with the 10mm hole over the spindle and firmly tapping the end of the dowel with a mallet. Then tap around the circumference of the dowel end until the back bearing is completely seated in the end of the valve casing. Now slip the rotor stop into place on the end of the rotor spindle and screw in the rotor stop screw. Assemble the remaining valves in the same way.

Replace the strings as in the diagram and adjust the key height by sliding the string around the rotor stop and rotor stop string screw. Tighten the screw just enough to hold but not cut into the string. Now check the key action. If the key binds somewhat it could be that the string is too tight. In that case loosen the key lever string screw and pull the string back through the hole a bit while re-tightening the screw.